In the fall of 2001, letters intentionally contaminated with Bacillus anthracis were mailed to individuals in Florida, Washington, D.C., and New York City. These events resulted in exposures both at the sites of delivery and also at sites the letters passed through in New Jersey, Pennsylvania, Virginia, Maryland, and Connecticut. In total, there were 11 cases of documented inhalation anthrax infections, including 5 deaths, and 11 cases of documented cutaneous anthrax infections. Antimicrobial prophylaxis for at least 60 days was recommended for about 10,000 individuals; ultimately, about 32,000 people actually received prophylactic therapy.
The public health crisis in antibiotic resistance generally focuses on nosocomial and community-acquired infections with organisms that have naturally become resistant to multiple agents. This situation has developed due to a combination of antibiotic use (including overuse and misuse) and the emergence of freely transmissible resistance determinant(s). Organisms that might be (or have been) used by bioterrorists could acquire antibiotic resistance not only naturally, but also as a result of intentional manipulation.
Ciprofloxacin, doxycycline, and penicillin G procaine (penicillin) are the three drugs currently approved for intravenous therapy of all forms of anthrax (cutaneous (skin), inhalation, and gastrointestinal) infection. Mobile elements that confer resistance to tetracyclines and penicillins can be introduced into B. anthracis and are functional; resistance to ciprofloxacin can be induced by passage in vitro. Thus, there is a real possibility of multiple drug resistant (MDR) anthrax and alternative agents effective against such strains are needed.